Oil recovery apparatus

ABSTRACT

A method and apparatus for recovering oil from oil-containing sorbents, such as drill cuttings obtained from drilling with an oil-based mud. The method includes peptizing the substrate with an acid reagent and direct thermal desorption with combustion effluent gases at high temperature under turbulent mixing conditions. Another method disclosed includes upgrading the oil in the substrate to improve one or more of the properties of the recovered oil relative to the oil in the substrate, such as, lower aromatics content, lower sulfur content, lower functional group content, higher saturates, higher viscosity, higher viscosity index, and any combination thereof. The apparatus provides for efficient recovery of oil from the substrate with a short residence time, high throughput, low residual oil content in the treated solids and/or high percentage of oil recovery. The apparatus may be transported to a remote location for on-site treatment of drill cuttings or other oil-containing solids.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. Ser. No. 13/180,379, filed Jul.11, 2011, now U.S. Pat. No. 8,356,678, which claims priority benefit toU.S. Provisional Application No. 61/408,494, filed Oct. 29, 2010, whichare hereby incorporated herein by reference.

FIELD OF THE INVENTION

This disclosure relates to the recovery of oil from solid substrates,and also to the upgrading of oil in a heterogeneous chemical-thermaldesorption system.

The composition of many oil-based drilling muds typically includes thefollowing compounds: (1) bentonite; (2) barite; (3) kerosene, diesel orother oil; (4) polymers; (5) sodium, calcium and potassium chlorides;(6) lime; and (7) water (invert emulsion). The inverse emulsiongenerally uses more oil than water. As used herein, the term “oil-basedmud” also includes synthetic muds that are sometimes classifiedseparately even though they contain appreciable amounts of hydrocarbons.

Conventional oil based drilling fluids may use oil containing as much as30% aromatics or more, such as, kerosene, diesel or refined Group I orGroup II base stocks, whereas synthetic drilling fluids may employ ahydrocarbon base stock with a higher viscosity (KV40 and/or KV100), ahigher viscosity index (VI), a lower pour point, a lower specificgravity, a higher flash point and a lower content of functional groupssuch as hydroxide, aryls, substituted aryls, halogens, alkoxys,carboxylates, esters, acrylates, oxygen, nitrogen, carboxyl, and thelike. On the other hand, Group III or Group IV (polyalphaolfins or PAO)base stocks can have a viscosity index of 120 or more, a kinematicviscosity of 3 to 3000 cSt at 100° C., a pour point of −20° C. or less,specific gravity less than 0.86 and a flash point of 200° C. or more.

In general, higher quality oils have lower aromatics and sulfur, andhigher saturates, viscosity and viscosity index. Aromatics content isimportant in drilling applications since oil with a high aromaticcontent as reflected by a low aniline point can cause elastomers used inO-rings and gaskets to swell and fail. The use of higher quality oils indrilling fluids may also allow the drilling fluid to perform under moresevere conditions, to last longer, to reduce wear on the drillingequipment, to use less energy, etc.

The physical nature of the oil based drill cuttings (OBDC) complicatesthe recovery of oil. Numerous attempts have been tried to recover orremove a high quality oil from the drill cuttings with limited success.For example, the industry has had a long-felt need to address one ormore of the following problems in the prior art OBDC treatmentprocesses: the quantity of oil recovered may be very low and/or theresidual oil remaining in the solids too high; the process or processingequipment may require excessive amounts of energy, require a longtreatment time, require large equipment not easily transported to aprocessing site, require excessive capital for expensive equipment, orentail excessive risk of explosion or other hazards; or the treateddrill cuttings may have a pH less than 6 or more than 8, i.e., the drillcuttings may be too acidic or especially too alkaline for environmentaldisposal; or the quality of the oil obtained may not be suitable forre-use in drilling muds, especially synthetic grade muds requiring oneor more of a higher flash point, viscosity and/or VI, and a lower pourpoint, specific gravity, aromatics content and/or functional groupcontent, relative to the oil typically present in and/or recovered froman OBDC treatment process.

There exists a need for efficient ways to obtain high quality oil fromsolids such as OBDC while removing sufficient oil from the solids forenvironmental disposal.

SUMMARY OF THE INVENTION

The present disclosure is directed to a method and apparatus forprocessing a substrate comprising oil bound to a sorbent material, andin a particular embodiment, to the efficient recovery of high qualityoil from oil based drill cuttings (OBDC) from drilling of oil and gaswells.

In an embodiment, a method comprises processing a substrate comprisingliquid bound on a solid sorbent material, wherein the liquid comprisesoil or a mixture of oil and water, wherein the bound liquid comprisesless than about 35 wt % of the substrate. The method comprises (a)peptizing a substrate with an acidic reagent under shear to obtain apeptizate having increased surface area; (b) mixing the peptizate with acombustion effluent gas under turbulent conditions in a thermaldesorption zone to heat the peptizate and desorb at least a portion ofthe oil from the sorbent material; and (c) separating the mixture into adilute phase and a dense phase, wherein the dilute phase comprises oilvapor. In an embodiment, the peptizing occurs at a temperature betweenabout 70° C. and about 105° C., preferably up to about 100° C.

In an embodiment, the combustion effluent gas comprises less than 1 vol% oxygen, preferably a fuel rich, oxygen lean combustion effluent, andis introduced into the thermal desorption zone at a temperature greaterthan 300° C., preferably greater than 500° C.

In an embodiment, the sorbent material in the dense phase, i.e., therecovered solids stream has an oil content less than the oil content ofthe sorbent material in the substrate, preferably less than about 3 wt%, more preferably less than about 2 wt %, and especially less thanabout 1 wt %, based on the weight of the recovered solids. In anembodiment, the peptizate and/or the recovered solids comprise a pHbetween 6 and 8.

Also disclosed is an apparatus comprising a substrate feed zone tosupply a charge of the substrate defined above to a peptizing zone. Inan embodiment, an acid feed system is provided to supply an acid reagentto the peptizing zone. In an embodiment, the peptizing zone comprisesone or more agitators to impart shear into the peptizing zone to producea peptizate. In an embodiment, a transfer zone is provided to supply thepeptizate from the peptizing zone to the thermal desorption zone. In anembodiment, a burner is disposed in fluid communication with the thermaldesorption zone to supply a combustion effluent gas comprising less than1 vol % oxygen to the thermal desorption zone at a temperature greaterthan 300° C. In an embodiment, the thermal desorption zone comprises oneor more agitators to promote vapor-solid mixing. In an embodiment, asolids disengagement zone is provided in fluid communication between thethermal desorption zone and a vapor recovery system. In an embodiment, asolids outlet from a housing for the thermal desorption zone is providedadjacent the solids disengagement zone.

Also disclosed is a transportable apparatus, comprising a feed hopper tosupply a charge of the substrate defined above to a peptizer comprisinga first fixed housing and one or more agitators. In an embodiment, anacid feed system is provided to supply an acid reagent to react with thesubstrate in the peptizer and form a peptizate. In an embodiment, atransfer zone is provided to supply the peptizate from the peptizer toan inlet end of a thermal desorber comprising a second fixed housing andone or more agitators, wherein the transfer zone provides a seal tofluidly isolate the peptizer from the thermal desorber. In anembodiment, a burner is provided in fluid communication with the thermaldesorber to supply a combustion effluent gas comprising less than 1 vol% oxygen at a temperature greater than 300° C. at the inlet end. In anembodiment, the thermal desorber comprises an agitator to createturbulence and promote mixing and heat transfer. In an embodiment, asolids disengagement zone is provided at an outlet end of the thermaldesorber opposite the inlet end for co-current operation to separate adilute phase from a dense phase. In an embodiment, the apparatus alsoincludes a vapor outlet and a solids outlet from the solidsdisengagement zone. In an embodiment, the apparatus includes atransportable platform on which the feed hopper, acid feed system,peptizer, burner, and thermal desorber are mounted, which may optionallybe wheeled, wherein the mounted first platform has an overall width ofless than 2.6 meters (102 inches), an overall length of less than 13.7meters (45 feet) and an overall height of less than 4.1 meters (13.5feet). In embodiments, a vapor recovery system is further provided influid communication with the vapor outlet to receive the dilute phase,wherein the vapor recovery system comprises at least one solidsseparator to remove entrained fines, at least one condenser to recoverliquid and a gravity separator to obtain oil and water streams, whereinthe vapor recovery system is mounted on the transportable platform withthe thermal desorber, on another transportable platform or a combinationthereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of an embodiment of the method disclosedherein.

FIG. 2 is a schematic diagram of a chemical-direct thermal desorptionapparatus for the upgrading, removal and recovery of oil from oil-baseddrill cuttings according to an embodiment;

FIG. 3 shows a perspective view of a peptizer according to oneembodiment;

FIG. 4 schematically shows the generally longitudinal flow patterninside the peptizer of FIG. 3;

FIG. 5 shows the rotation of the shafts and the transverse flow patternsinside the peptizer of FIGS. 3 and 4;

FIG. 6 shows a partial cut-away view of a thermal desorber according toan embodiment;

FIG. 7 shows a longitudinal sectional view in elevation of the thermaldesorber of FIG. 6;

FIG. 8 is a sectional view showing the agitator paddles in the thermaldesorber of FIG. 7 as seen along the lines 8-8;

FIG. 9 is a sectional view showing the agitator supports in the thermaldesorber of FIG. 7 as seen along lines 9-9;

FIG. 10 is a schematic overview of a vapor recovery system according toone embodiment;

FIG. 11 is a schematic side elevation of a first transportable unitconfigured for operation according to an embodiment;

FIG. 12 is a schematic side elevation of a second transportable unitconfigured for operation according to an embodiment; and

FIG. 13 is a schematic plan view of the first and second transportableunits of FIGS. 11-12 configured for transport according to anembodiment.

DETAILED DESCRIPTION

The present disclosure is directed to a method and apparatus forprocessing a substrate containing oil to upgrade and/or recover the oiltherein, in particular, the treatment of oil based drill cuttings (OBDC)from the drilling of oil and gas wells. The instant disclosure is alsodirected to the treatment of oil based drill cuttings for environmentaldisposal. Although the skilled person will appreciate the method andapparatus can be used to treat other substrates, especiallyoil-containing substrates having a peptizable matrix component such asacid-reactive clays or minerals wherein the oil is bound to a solidsorbent material, the following description refers to OBDC as anonlimiting example for illustrative purposes.

The process provides fast and efficient processing of OBDC which can beachieved with relatively small peptizing, combustion, desorption, solidsrecovery, vapor recovery and/or oil recovery process units and shortresidence times. The total processing time for the solids is on theorder of minutes, for example. In an embodiment, the processingequipment can be transportable, e.g., skid-mounted or trailer-mounted,for transportation to the drilling site or other on-site processinglocation. The process provides in one embodiment a relatively high oilrecovery, e.g., 50, 60, 70, 75 or even 80 percent or more of the oil inthe OBDC or other substrate. Furthermore, in a specific embodiment, therecovered oil may surprisingly have improved properties relative to theoil in the OBDC, e.g., a higher viscosity and/or lower aromatichydrocarbon concentration that of the oil present in the substrate.

In an embodiment, the oil in the bound liquid in the substrate comprisesmore than 2 wt % or more than 1 wt % aromatic hydrocarbons, by weight ofthe oil in the OBDC, and may contain as much as 20 wt %, 25 wt %, 30 wt% or more aromatic hydrocarbons, by weight of the oil in the OBDC,whereas the recovered oil comprises less aromatic hydrocarbons,preferably less than 2 wt % or more preferably less than 1 wt % aromatichydrocarbons, by weight of the recovered oil. As used herein, aromaticscontent is determined as the total BTEX(benzene-toluene-ethlylbenzene-xylene) according to US EPA 8260. In anembodiment, the viscosity of the recovered oil may be increased relativeto the viscosity of the oil present in the substrate. In an embodiment,the recovered oil has a viscosity at 40° C. (KV40) of greater than 2cSt, wherein the viscosity is determined according to ASTM-D88.

In an embodiment, the recovered oil is suitable for use in a drillingfluid. For example, the recovered oil in one embodiment is furtherprocessed by formulating a drilling fluid based on the oil, in oneembodiment as the equivalent of a synthetic oil base stock. The drillingfluid can also be formulated with a brine component, e.g., as aninternal phase, that is also recovered from the OBDC or a high-liquid(greater than 35 wt % liquids or where the liquid can be readilyrecovered by filtration, pressing, centrifugation or the like) waterbased or oil based drill cuttings or water based or oil based spentdrilling fluids.

The exact mechanism for the improvement of the qualities and propertiesof the recovered oil are not known, but it is theorized that the oil mayundergo various reactions in the low-oxygen or reducing atmosphere inthe chemical-thermal treatment such as cracking, reforming,oligomerization, hydrogenation, dehydrogenation, coking, isomerizationor the like, and further that the drill cuttings or other sorbentmaterial, particularly by pretreatment or “activation” by the acidtreatment in the peptizing step, may act as a catalyst for theconversion of the hydrocarbons to paraffinic and/or alicyclichydrocarbons and/or conversion of heterohydrocarbon components tonon-functionalized hydrocarbons. It is also theorized that themechanism(s) may selectively favor reaction of the aromatic compoundsand devolatilization of the paraffinic compounds. The invention is,however, not bound by any particular theory or reaction mechanism.

FIG. 1 shows a method 10 according to an embodiment of the presentdisclosure to separate and recover oil from a substrate feed 12 whichmay be OBDC and/or other oil-containing materials. The method 10 mayinclude acid addition 14 and peptizing 16, wherein the substrate iscontacted with an amount of an acidic reagent for a period of time, at atemperature, and under shear to react at least a portion of thesubstrate to produce a peptizate having an increased surface areacompared to the substrate. The acidic reagent can include a mineral acidadded in step 14 to the substrate at one or more stages before or duringthe peptizing step 16.

Combustion 18 provides a hot effluent gas at a temperature greater than300° C. and comprising less than 1 vol % oxygen for mixing anddesorption 20 to mix the peptizate with the hot gas under turbulentconditions to heat the substrate and desorb at least a portion of theoil. Solids recovery 22 may involve separating the mixture from thesubstrate mixing/desorption step 20 to obtain a dilute phase comprisingvapor including devolatilized oil from the substrate and a dense phasecomprising oil-lean solids 24. Solids recovery 22 may also includeremoval of entrained solids from the dilute phase with cyclonicseparation, filtration, electrostatic precipitation, scrubbing or thelike or any combination thereof.

In oil recovery step 26, oil 28 is recovered from the dilute phasevapors by, for example, condensation and gravity separation of thecondensate into respective streams of oil 28 and an aqueous phase 30. Ifdesired, the recovered oil stream 28 may be collected for furtherpurification and/or use in the process, e.g., as a fuel in combustionstep 18. In an embodiment, the oil purification may optionally includeone or more additional processes to further purify the recovered oil fora particular end use. Examples include distillation, filtering,treatment with activated carbon, absorbents, adsorbents, and/or thelike, reaction with various materials to remove and/or convertimpurities contained therein, fractionation, ion exchange, and/or thelike, depending on the desired properties of the oil and/or dependent onthe intended use of the subsequently purified recovered oil.

FIG. 2 shows an embodiment of the apparatus, generally referred to as32, wherein the substrate from substrate feed zone 34 and acid from acidfeed system 36 are supplied to a peptizer 38 comprising a first housing40 equipped with one or more high-shear agitators 42. The first housing40 is preferably fixed and fluidly sealed. A transfer zone 44,preferably comprising a rotary valve 46 or other means to fluidlyisolate the peptizing zone 38, is provided to supply the peptizate to aninlet end of thermal desorption zone 48 within second fixed housing 50equipped with one or more turbulence-generating agitators 52. Burner 54is provided to supply hot combustion effluent gas to the thermaldesorption zone 48 to heat the peptizate and desorb oil from the sorbentmaterial.

The second housing 50 is preferably a fixed horizontal cylinder equippedwith a solids disengagement zone 54 opposite the inlet end of thethermal desorption zone 48 and a solids outlet 56 adjacent thedisengagement zone 54 to receive disengaged solids therefrom. The solidsdisengagement zone 54 and solids outlet 56 are preferably spaced awayfrom the agitator 52 to promote solid separation and settling, i.e., theagitator 52 preferably terminates adjacent the solids disengagement zone54 and does not extend into the solids disengagement zone or above thesolids outlet 56. The solids disengagement zone 54 may be provided witha hood 58 or other relatively large cross-sectional and/or low flowvelocity plenum to promote solids settling and provide a solids-leandilute phase for processing in vapor recovery system 60.

The Substrate

The substrate which is processed or treated according to variousembodiments comprises liquid bound on or within a solid sorbentmaterial, wherein the liquid comprises oil or a mixture of oil andwater. Although the substrate to be treated is described herein withspecific reference to drill cuttings as one example, and especiallydrill cuttings obtained from operations with oil-based drilling muds(oil based drill cuttings or OBDC), other contaminated orenvironmentally hazardous wastes or substrates can also be treated usingthe present methodology and apparatus, especially clay-containingwastes. Drill cuttings can contain large quantities of clay because theoil deposits and other strata typically have a high content of clay.

In one embodiment, the substrate can be provided by contacting a sorbentmaterial containing acid-reactive component(s) with oil in a suitableoil-sorbent mixing device, for example, where the oil contains aromaticsor has a relatively poor quality and it is desired to upgrade the oilaccording to the process of the present invention. In this embodiment,the process may include a separate oil-sorbent contacting step or theoil sorbent contacting may occur in the peptizer, e.g., in anoil-sorbent contacting zone upstream from the peptizing zone or aportion thereof. In an embodiment, the solids recovered from the thermaldesorber can be recycled as the sorbent to the oil-sorbent contactingzone or step.

Suitable substrates include OBDC containing 50 wt % or less totalliquids, based on the total weight of the substrate, wherein thesubstrate is generally free of free liquid, i.e., the liquid will notreadily separate from the OBDC by gravity. In various embodiments, thesubstrate may contain less than or equal to about 35 wt % total liquids,less than or equal to about 30 wt % total liquids, less than or equal toabout 25 wt % total liquids, less than or equal to about 20 wt % totalliquids, less than or equal to about 15 wt % total liquids, or less thanor equal to about 10 wt % total liquids, and may contain at least about5 wt % oil, at least about 10 wt % oil, at least about 15 wt % oil or atleast about 20 wt % oil, based on the weight of the substrate (liquidand sorbent). Substrates with greater amounts of oil can be processedaccording to the present embodiments, but, when economically possible,it may be desirable according to an embodiment to alternatively treatsuch substrates by other steps such as centrifugation, gravity settling,solvent extraction, or the like, prior to the instant process, to removethe bulk of the oil which may be readily removed by more conventionalmeans.

If desired, in one embodiment, the substrate may be amended by theaddition of lime or another acid-reactive component, e.g., where thesubstrate is deficient in acid-reactive components. OBDC normally have apH in the range of about 10-12, and are sufficiently reactive withmineral acid to a pH in the intermediate peptized material and recovereddevolatilized substrate of about 6-8. However, where the OBDC have anunusually low pH the process can benefit by the addition of alkalineearth, e.g. lime, to obtain a pH in the 10-12 range.

If desired, in another embodiment, the OBDC may optionally bepretreated, and/or treated in the peptizer, with a demulsifier such asdodecyl benzene sulfonate.

Peptizing

The peptizing of the substrate is a physical-chemical process in whichthe sorbent in the substrate is induced to quickly expand by contactingwith one or more mineral acid reagents thereby increasing its volume tofacilitate the disintegration or dispersion of agglomerated particlesand expose surface area to facilitate the release of liquid in thesubsequent thermal desorption step. Peptizing thus includes contactingthe substrate with an amount of a mineral acid under high shearconditions within a peptizing zone.

In an embodiment, the mineral acid reagent, also referred to herein asthe mineral acid, is added to the substrate in an amount sufficient toproduce a peptizate having a pH between 6 and 8, preferably a pH between6.5 and 7.5. The mineral acid may be added at between 1 wt % and 100 wt%, preferably between 2 wt % and 20 wt %, based on the total amount ofsubstrate material present, to produce a peptizate. The mineral acid inone embodiment is typically added at 4 wt % to 10 or 12 wt %, based onthe total weight of the substrate.

Importantly, the more water present in substrate the more acid istypically added. In an embodiment, the proportion of acid supplied tothe peptizing zone can be employed as a temperature control tool in thethermal desorption zone, for example, if the steady state temperature ofthe thermal desorption zone increases or decreases due to decreased orincreased water content of the OBDC supplied to the peptizer, then theacid addition rate may be respectively increased or decreased to accountfor the fluctuation. This can be an important control mechanism sincethe water content of the OBDC can vary considerably between and withinbatches, e.g., water may drain from the uppermost OBDC layers in thefeed or storage hopper into the lower layers so that the lower layersmay contain more water than the upper layers, or the upper layers maybecome wet from precipitation or humidity or other contact with water;and also because of the difficulty of adjusting the temperature of thecombustion effluent gases supplied from the burner while maintaining lowoxygen or substoichiometric oxygen:fuel ratios (fuel rich).

In addition, depending on the water content and the composition of thesubstrate, in one embodiment the amount of mineral acid added to producea peptizate suitable for desorbing would result in a peptizate having apH of less than 6. In an embodiment wherein the addition of an amount ofmineral acid to produce a peptizate having a pH of 6 or less would nototherwise be suitable for desorption, additional acid and an alkalinereagent may be added to the peptizing zone in neutralizing amount, e.g.,an amount of additional acid and alkaline reagent such as alkaline earthsufficient to produce a peptizate having a pH between 6 and 8. Wherealkaline reagent is employed it is preferably added in an alternatingstage or stages with the acid.

The acid may be diluted with water to achieve the desired result and/orcontrol, but is preferably added as a concentrate or neat to obtain ahigher temperature in the peptizate.

Suitable mineral acids include, for example, sulfuric acid, oleum,phosphoric acid, nitric acid, hydrochloric acid, combinations thereof,and the like. In an embodiment, the mineral acid preferably comprisesconcentrated (98+wt %) sulfuric acid.

The mineral acid may be added to the substrate as it enters thepeptizing zone, or may be added step wise in one or more stages duringpeptizing, under high shear mixing and/or kneading conditions. Examplesof high shear conditions include those present in various kneaders,ribbon blenders, paddle mixers, and the like, known to one of skill inthe art.

In an embodiment, the oil based drill cuttings and the mineral acid arecontacted for a period of time and at conditions of temperature andshear sufficient to allow them to react chemically inasmuch as the OBDCare broken into smaller particles and/or a clay solid shale matrix maybe expanded (e.g., intercalated, exfoliated, delaminated, opened, and/orthe like) to permit the immigration of the inverse oil in water emulsioncontained within the substrate to a point nearer to the surface of theparticles.

In an embodiment, the substrate is preferably provided as a continuousstream into the peptizing zone. Peptizers such as those disclosed in myearlier patents U.S. Pat. Nos. 7,690,445, 7,481,878, 6,978,851 and6,668,947, which are hereby incorporated herein by reference in theirentireties for all purposes to the extent they are not inconsistent withthe present disclosure, may be suitably employed. As shown in FIG. 3, inan embodiment, the peptizer 62 comprises the first housing 40 for thepeptizing zone. The housing 40 is preferably fixed and includes an uppersubstrate inlet 64 at one end of the peptizer 62 and a lower solidsoutlet 66 (a discharge) at the other end of the peptizer 62. If desired,the acid may also be introduced in the inlet 64 with the solids.Optionally, peptizer 62 may include an upper exhaust vent 68 preferablyin an upper surface adjacent substrate inlet 64, one or more additionalports 70 which may include steam inlets, acid reagent inlets, causticreagent inlets, vapor outlets, liquid outlets, solids outlets, and/orthe like, which may be located in an upper surface and/or a lowersurface of peptizer 62 upstream of substrate inlet 64, between substrateinlet 64 and solids outlet 66 or downstream of the solids outlet asdesired for co-current or countercurrent operation. In one embodiment,the vent 68 and port(s) 70, if present, are sealed so as to fluidly sealthe peptizer 62, except that the vent 68 and port(s) 70 may be equippedwith a pressure relief valve or rupture disk so as to preventoverpressuring the peptizer 62, e.g., in the event peptizer 62 isoverheated above the boiling point of water or other liquid in thesubstrate, in which case the vent 68 or port 70 may be connected to thevapor recovery system 60 (see FIG. 2).

In an embodiment as best seen in FIGS. 3-5, the peptizer 62 comprises atleast one agitator 72 to impart shear into the acid/substrate mixture.The agitator 72 may comprise a rotating shaft 74, preferably a pair ofrotating shafts 74, longitudinally aligned in first fixed housing 40,which may be rotated in opposite or complementary directions. Aplurality of paddles, pins, plows, blades and/or the like, referred toherein as blades 76, may be positioned along the length of shaft(s) 74.The blades 76 can be pitched to facilitate maximum shear conditions foragitation and/or movement of the solids in a forward and/or partialback-mixing within peptizer 62.

In embodiment, peptizer 62 is operated at a temperature of greater thanor equal to about 50° C. and 200° C., preferably between about 70° C.and 100° C., more preferably between 75° C. and 90° C. In oneembodiment, the peptizer 62 has a maximum operating temperature at orbelow the boiling point of the liquid bound to the substrate at anabsolute pressure of 1.25 atmospheres, preferably below the boilingpoint of the bound liquid at atmospheric pressure; and in anotherembodiment, the peptizer 62 is operated at about atmospheric pressure,i.e., from about 0.9 to about 1.25 atmospheres absolute, or belowatmospheric pressure, preferably from −0.1 to 0 atmospheres gauge.Subatmospheric pressure may be maintained in the peptizer 62, forexample, by connecting vent 68 or a port 70 to an induced draft fan invapor recovery system 60, or by sealing the inlet 64 and outlet 66 withsuitable mechanical devices such as rotary valves which permit somevapor leakage or bypass from the peptizer 62 into a subatmosphericsystem such as where subatmospheric pressure is provided in thermaldesorption zone 48 (see FIG. 2). In an embodiment, the peptizer 62 mayheated or cooled to maintain the desired temperature. In a preferredembodiment, however, the peptizer 62 is insulated and operatedadiabatically wherein the exothermic reaction between the acid reagentand acid-reactive materials in the substrate and/or heat of dilution ofthe acid reagent in the liquid present in the substrate feed provideinternal heating. Where present, heating may occur through indirectheating e.g., via external application of a heat transfer medium,electrical heating, and/or the like.

FIGS. 4 and 5, respectively, show a schematic plan view of the movementof material in peptizer 62, and a schematic elevation of the movement ofmaterial in peptizer 62. The arrows in FIGS. 4 and 5 show the horizontaland vertical direction of the movement of the solids and the rotation ofthe shafts. If desired, baffles (not shown) may be positioned betweenadjacent blades 76. The peptizer 62 may further comprise a plurality ofreactors or stages in sequence, either separate or within the samehousing.

The internal design and construction materials for the peptizer 62 arepreferably such as to resist extreme pH environments within the process,especially when heat is provided through direct or indirect heating ofthe peptizer 62 and/or via the exothermic reaction between the substrateand the mineral acid, the mineral acid and a caustic reagent, and/or thelike. The peptizer is preferably comprised of stainless steel alloy.

The speed of the material throughput, as well as the specific materialsused to manufacture the peptizer 62 may be selected to prevent theviscoelastic hydrocarbon and cuttings matrixes typical of oil baseddrill cuttings from sticking to the walls thereof. In an embodiment, thespeed of agitator 72 is critical in creating particles suitable for thedesorption step of the substrate contaminants. If the impeller speed istoo slow, the substrate will not be adequately contacted with thereagents resulting in poor contact between the contaminated particlesand the acid. If the speed of the impeller is too fast, energy is wastedwith no improvement in reaction conditions including reduction inparticle size and/or expanding of the particles of the substrate (i.e.,the substrate) to be treated.

The moving speed at the tip of the blades 62 in one embodiment mayideally be between 2 and 8 m/s (7 and 26 ft/s) on rotation. Morepreferably, the tip speed is between 2 and 5 m/s (7 and 16 ft/s), andespecially between 2.5 and 3.5 m/s (8 and 12 ft/s). As one example for amixer treating 10 metric tons per hour of drill cuttings (5 m³/h or 180ft³/h), the peptizer can have twin parallel shafts approximately 3 m (10ft) long, running the length of the mixer, each with at least 30paddles/shaft and a 0.4 m (1.3 ft) diameter. In another embodiment, themoving speed at the tip of the blades 62 is approximately 0.01 to 1 m/s,preferably about 0.2 m/s (0.7 ft/s) on the translation in bothdirections

In an embodiment, the total residence time of the substrate within thepeptizer 62 is less than or equal to about 2 minutes, preferably theresidence time within the peptizer is between about 10 and 120 seconds,preferably less than 100 seconds, preferably less than 90 seconds,preferably less than 80 seconds, preferably less than 70 seconds,preferably less than 60 seconds, preferably less than 50 seconds,preferably less than 40 seconds, with less than 30 seconds being morepreferred.

As one example for a reactor treating 30 metric tons per hour of drillcuttings (15 m³/h), the peptizer 62 has twin parallel shaftsapproximately 3.66 m (12 ft) long with 74 paddles/shaft and a 457 mm(18-in.) diameter. The total reaction (residence) time preferably doesnot exceed 60-80 seconds inside the reactor. The reaction processrequires vigorous agitation. The energy for agitation in the peptizer 62desirably does not exceed 1.12 kW (1.5 hp) per each metric ton oftreated matrix per hour. For example, to treat 30 metric tons per hourof contaminated drill cuttings, the total power required for driving thepeptizer agitator is preferably 33.6 kW (45 hp) or less.

The temperature at the inlet of the peptizer 62, which represents thethermal equilibrium of the mixed feeds (ignoring any heats of reactionand/or dilution) is preferably ambient to slightly above ambient, e.g.,20 to 30° C., although in one embodiment the substrate, the acid reagentand/or other feeds may be preheated. The temperature of material withinthe peptizer may increase due to the heat generated by the reaction ofthe mineral acid with the substrate being treated, by the heat ofdilution of the mineral acid in the water present in the substrate,and/or via (optional) application of heat to the peptizer itself. Thetemperature at the exit of peptizer is preferably greater than or equalto about 70° C., and preferably less than or equal to about 100° C.

Thermal Desorption

In an embodiment as shown in FIG. 2, the peptizate is transferred fromthe peptizing zone 38 through the transfer zone 44 into the secondhousing 50 comprising the thermal desorption zone 48. The thermaldesorption zone 48 is in fluid communication with burner 54 whichsupplies combustion effluent gas. In an embodiment, the combustioneffluent gas comprises less than 1 vol % oxygen and is supplied to thethermal desorption zone at a temperature greater than 300° C.

In an embodiment, the thermal desorption zone 48 comprises an agitator52 to create turbulent conditions and promote rapid heat transfer. Thepeptizate is mixed with the combustion effluent gas under turbulentconditions in the thermal desorption zone 48 to heat the peptizate anddesorb at least a portion of the oil from the sorbent material. Themixture exiting the thermal desorption zone 48 is separated into adilute phase comprising oil vapor from the sorbent and a dense phasecomprising the sorbent, wherein the dense phase has an oil content whichis less than the oil content of the sorbent material present in the feedsubstrate and/or in the peptizate.

In an embodiment, the temperature of the combustion effluent gas issufficient to provide a temperature of the vapor phase exiting thedesorber in a range from a lower limit of 180° C., 200° C., 220° C.,235° C., or 250° C. to a higher upper limit of up to 500° C., 400° C.,350° C., or 300° C. In general, the thermal equilibrium temperature ofthe dense phase solids recovered from the desorber is about 10° C. to50° C. less than the dilute phase vapor, preferably 20° C. to 40° C.less, more preferably 25° C. to 35° C. less. In an embodiment, slightlynegative pressure, for example, 0.8 to 0.99 atmospheres absolute or−0.01 to −0.2 atmospheres gauge, is continuously maintained in thethermal desorption zone, e.g., by withdrawing vapor or a dilute solidsphase via an induced draft fan in the vapor recovery system 60, and ifdesired a safety valve such as a pressure relief valve and/or rupturedisk can be provided in the case of overpressure, e.g., the safety valvecan be calibrated at about 0.1 MPa gauge (about 14.7 psig) or 0.05 MPagauge (7.35 psig) or 0.03 MPa gauge (4.4 psig) or 0.02 MPa gauge (3psig).

In an embodiment, the average residence time in the thermal desorptionzone 38 of the dense phase (e.g., the solids present in the peptizate)is less than or equal to about 5 minutes, preferably less than or equalto about 4 minutes, with less than or equal to about 3 minutes beingstill more preferred. In an embodiment, the average residence time inthe thermal desorption zone of the dilute phase is less than 1 minute.In an embodiment, the temperature and residence time in the thermaldesorption zone is sufficient to produce a processed solid having lessthan or equal to about 3 wt % residual oil, preferably less than orequal to about 2.5 wt % residual oil, preferably less than or equal toabout 2 wt % residual oil, preferably less than or equal to about 1.5 wt% residual oil, preferably less than or equal to about 1 wt % residualoil, preferably less than or equal to about 0.5 wt % residual oilpresent, based on the total amount of solids and oil in the dense phase.

In an embodiment, the dense phase has an average amount of residual oilwhich represents greater than or equal to about a 50% reduction in oilcompared to the oil content in the original substrate, preferablygreater than or equal to about a 60% reduction, preferably greater thanor equal to about a 70% reduction, preferably greater than or equal toabout an 80% reduction, preferably greater than or equal to about a 90%reduction, preferably greater than or equal to about a 95% reduction inoil content compared to the oil content of the original substrate.

In another important embodiment, the oil is selectively devolatilized inthe thermal desorption step and/or otherwise upgraded to improve one ormore of the properties of the recovered oil relative to the oil in theOBDC or other substrate, such as, for example, lower aromatics content,lower sulfur content, lower functional group content, higher saturates,higher viscosity, higher viscosity index, and any combination thereof.Without being bound by theory, reactions that may occur in the thermaldesorber include cracking, hydrocracking, steam cracking, hydrogenation,dehydrogenation, isomerization, etc. The combustion effluent gas maycontain reactive species such as, for example, hydrogen, hydrocarbons,steam, carbon monoxide, carbon dioxide, and the like. In one embodiment,the combustion effluent gas is free of oxygen, e.g., less than 1 vol %oxygen, preferably less than 0.1 vol % oxygen.

In one embodiment, the OBDC or other substrate may act as a catalyst oras a support for catalysts, e.g., the peptization with acid may exposeor form catalytically active surfaces in the sorbent material. In afurther embodiment, the OBDC or other substrate may be amended by theaddition of a catalyst such as one or more of zeolites, aluminates,silicates, aluminum silicates, noble metals, etc., added in thepeptization step or in the thermal desorber.

In one embodiment of a method, oil to be upgraded may be contacted withthe substrate and then subjected to turbulent, low oxygen, thermaldesorption. In this embodiment, the solids recovered from the thermaldesorber may be recycled for use as the substrate, or the substrate maybe OBDC which are not saturated or are supersaturated with oil or anoil-water mixture, or the substrate may be a clay-containing solid or asolid containing any acid-reactive mineral or an oil upgrading catalyst.The oil may be a single phase or it may be an emulsion or invertemulsion. For example, the oil can be a waste oil, sludge, emulsion,etc., or a petroleum fraction. The oil-substrate mixture is optionallypeptized with an acid reagent and/or optionally preheated to 70-100° C.

In an embodiment, a suitable thermal desorption zone may be dimensionedand arranged to process about 20 metric tons/hr of pretreated orpeptized ODBC to produce a final material comprising less than or equalto about 2.5 wt % oil, less than or equal to about 1.5 wt % oil, or lessthan or equal to about 1 wt % oil, based on the total weight of theoutput material. In an embodiment, at least a portion of the oil presentin the dilute phase is recovered in the vapor recovery system 60, and invarious embodiments, the recovered oil comprises at least 50 wt % of theoil originally present in the substrate, or at least 60 wt % of the oiloriginally present in the substrate, or at least 65 wt % of the oiloriginally present in the substrate, or at least 70 wt % of the oiloriginally present in the substrate, or at least 75 wt % of the oiloriginally present in the substrate, or at least 80 wt % of the oiloriginally present in the substrate, or at least 85 wt % of the oiloriginally present in the substrate.

In an embodiment, heat is supplied directly to the thermal desorptionzone 48 in the form of combustion effluent gas by the burner 54 which isdischarged into the thermal desorption zone. In an embodiment, theburner 54 preferably includes a combustion chamber positioned such thatthe hot combustion effluent gas enters the thermal desorption zone 48,but the burner is spaced away from the thermal desorption zone such thatthe flame does not impinge directly on the sorbent so as to avoidexcessive pyrolysis or combustion of the oil present in or with thepeptizate. In an embodiment, the burner 54 may operate at stoichiometricor sub-stoichiometric oxygen levels to control the amount of oxygenentering the thermal desorption zone to avoid or limit combustion orother oxidation of the oil present in or with the peptizate. In anembodiment, oxygen is desirably excluded from the combustion effluent bysetting the desired fuel rate to the burner, adjusting the air oroxygen-enriched air supplied to find the maximum flame temperature, andthen slightly reducing the air or oxygen-enriched air to reduce theflame temperature, e.g., 5° C., 10° C., 20° C. or 30° C. below themaximum flame temperature. For example, the burner in one embodiment issupplied with 90 to 99 percent of stoichiometric air, preferably 95 to98 percent of stoichiometric air.

If desired, a temperature moderator such as supplemental water and/orsteam may be injected into the combustion effluent gas to moderate thetemperature within the thermal desorption zone 48 to avoid overheatingof the material being treated therein. Any suitable fuel supply may beused, e.g., natural gas, fuel oil, recovered process oil, or acombination thereof. The combustion effluent gas may be supplied to thethermal desorption zone at a temperature from about 300° C. to about1200° C.

In an embodiment, as shown in FIGS. 6-9, the thermal desorption zone 48is located within a desorber 100 which includes a generally cylindricalfixed housing 102. The peptizate inlet 104 and solids outlet 106 arepreferably controlled by respective rotary valves 108, 110 (see FIG. 6)or other similar device to prevent oxygen from entering and/or hydrogen,carbon monoxide and hydrocarbon vapors from exiting the otherwisefluidly sealed desorber 100. An agitator 112 comprises a rotating shaft114 and a plurality of radially extending paddle assemblies 116. Theshaft 114 is centrally located, extends longitudinally through thedesorber 100 and is supported by end bearings 118 and intermediatebearings 120 carried on bearing support assemblies 122. The end bearings118 should be sealed to inhibit fluid communication outside the desorber100.

As shown in FIGS. 8-9, the housing 110 may optionally berefractory-lined and include, for example, a coaxial steel outer wall124 and/or one or more refractory linings such as outer refractory layer126, inner refractory layer 128 and surface layer 130. The outerrefractory layer 126 in one embodiment is a concrete layer formed fromsteel-reinforced gypsum cement, and inner layer 128 in an additional oralternate embodiment comprises a cast refractory or refractory bricks.Skin layer 130 is disposed between an inner surface of layer 128 and thecylindrical surface defined by the rotation of the paddle assemblies 116about the shaft 114, and may be formed in situ by the deposition ofsubstrate particles which become baked onto the surface of layer 128.Additional insulation materials e.g., cast or brick refractorymaterials, insulation, sound abatement materials, and the like, may beemployed inside or outside the unit to further improve the efficiency ofthe unit by attenuating the escape of heat.

In an embodiment, the combustion effluent gas 132 may enter the desorber100 at a hot gas inlet 134 located in a lower portion of the inlet endbelow the peptizate inlet 104 and pass co-currently with the solids togas outlet 136 located above the solids outlet 106. Co-current flowfacilitates movement of the solid particles toward the exit location andalso facilitates temperature moderation in the thermal desorption zone,which may be helpful to avoid or minimize coke or carbon formation fromoil residue which can otherwise occur if the temperature within thethermal desorption zone 48 is too high, which can in-turn inhibit masstransfer and lead to losses in the amount of oil that can be recovered.The presence of coke or carbon deposits on the treated solids can alsodiscolor the treated solids, e.g., gray or black, which may serve as anindication to one of skill in the art that the internal temperature istoo high for a particular application. In an alternate embodiment, thegas and solids may enter and exit from opposite ends in a countercurrentconfiguration.

In an embodiment, the shaft 114 is preferably rotated such that the tipspeed of the paddle assemblies 116 is between 0.1 and 20 m/s, preferablybetween 0.5 and 10 m/s, more preferably between 1 and 8 m/s, and morepreferably between 2 and 6 m/s. The rotation creates turbulence withinthe thermal desorption zone to improve the gas-solid contact of thesubstrate undergoing the desorption step with the hot gases and thus topromote heat and mass transfer, reducing the residence time required tocomplete the desired heat and mass transfer within the thermaldesorption zone. Insufficient agitation can increase the residence timeneeded or reduce the efficiency of the oil recovery. Too much agitationcan unnecessarily increase the power requirements, speed wear and tearon the equipment and produce excessive fines which are undesirablyentrained in the dilute phase and can lead to problems with finesremoval or plugged lines and equipment in the vapor recovery system 60.

The paddle assemblies 116 can be pitched as desired to advance thesolids material through the desorber 100, but are preferably notpitched. Similarly the desorber 100 can be sloped to facilitate orinhibit the movement of solids through the unit, but is preferablylevel. The turbulence in the desorber 100 and the relatively highvelocity of the gas through the unit are preferably sufficient toadvance the solids to the solids outlet 106. The space above the solidsoutlet 106, which is preferably located through a lower surface of thedesorber 100, is desirably free of rotating paddle assemblies 116 so asto promote solids disengagement from the dilute phase or vapor. Solidsdisengagement is also promoted by providing an exit conduit or hood 58of relatively large cross sectional area so as to reduce the flowvelocity and allow solids to settle, i.e., where the fines entrainmentis limited to particles having a terminal velocity which is less thanthe velocity of the exiting vapor. Increasing the height of the hood 58and limiting agitation in the space below and/or adjacent to the vaporoutlet 136 can also be beneficial to promoting solids disengagement.

The dilute phase produced in the thermal desorption zone may comprisefluidized solid particles of the sorbent and other materials. It isgenerally desirable to minimize solids entrainment in the dilute phase.Therefore, in one embodiment, the desorber 100 comprises a solidsdisengagement zone 54 having a relatively low velocity and turbulencerelative to other areas of the thermal desorption zone, which allowsentrained particles to drop out of the dilute phase before exiting thethermal desorption zone. The solids disengaged in the solidsdisengagement zone are returned to the solids adjacent a bottom surfaceof the thermal desorption zone and discharged from the thermaldesorption zone at a solids discharge 51. In an embodiment, solidsdischarge 51 may comprise a desorber outlet rotary valve 44.Disengagement zone 96 may also comprise an impingement plate, demisteror similar devices (not shown), to facilitate solids disengagement fromthe dilute phase.

In an embodiment, the first fixed housing and the second fixed housingare located in a single housing, separated from one another. In anotherembodiment, the thermal desorption zone is a different type of reactorwhich achieves the same mass and energy transfer under high shear orturbulent conditions to mix and heat the solids being treated with thecombustion effluent gas, such as, for example, a fluid bed reactor, amoving bed reactor, a riser reactor, any combination thereof, or thelike.

The solids are recovered from the thermal desorber below the solidsdisengagement zone. A rotary valve may be used to inhibit gas fromescaping from the desorber and air from entering the desorber. Ifdesired, the solids may be sprayed with water for cooling and/or dustcontrol or to enhance the desired water content of the solids. In oneembodiment, the recovered solids from the thermal desorber have aparticle size distribution comprising 90 wt % or more of the particleshaving a mesh size greater than 200 mesh, e.g., 90 wt % or more greaterthan 74 microns, and alternatively or additionally at least 80 wt % ofthe particles having a mesh size less than 40 mesh, e.g., 80 wt % ormore smaller than 420 microns. The solids may be further processed toremove additional oil, or may be disposed of, e.g. solids containingless than 1 wt % oil can usually be disposed of in an environmentallyresponsible manner.

Vapor and Oil Recovery

In an embodiment, the dilute phase exiting the solids disengagement zoneof the thermal desorber may comprise some entrained fines, desorbedhydrocarbons (e.g., oil) and water (steam), in addition, of course, tothe combustion gas effluent and any gaseous reaction products. Thedilute phase may also comprise combustion gas produced by the burner.The dilute phase may further include particulate matter, which isentrained in the dilute phase during thermal desorption. The dilutephase leaving the thermal desorber is typically at a temperature between100° C. and 800° C., preferably greater than or equal to about 150° C.,preferably between 180° C. and 350° C., more preferably about 180° C. toabout 325° C. or more preferably between 200° C. and 300° C. The volumethe dilute phase depends on the feed rate through the thermal desorptionzone, the temperature of the thermal desorption zone, the amountinitially present in the substrate, the amount of materials added duringthe process, and the like.

In an embodiment, dilute phase may be further processed in a vaporrecovery system 60 comprising various separation and purificationdevices, heat exchange devices, gas-liquid contact devices, scrubbers,decanters, and the like, to remove particular matter present in thedilute phase, to condense and recover the hydrocarbons and/or waterpresent in the dilute phase, to recover heat present in the dilute phasefor subsequent use in the process or elsewhere, and/or the like.

Represented generally as 60 in FIG. 2, and as shown in FIG. 10, vaporrecovery system 60 may include one or more of a cyclone 150, knock downtower 152 or other gas-solids separator or combination thereof, and/orthe like, to remove any entrained particulate solids. If solids,especially sub 4-micron particles, are not removed and are present inthe oil-water condensate, a rag emulsion may form which can be difficultto remove. The cyclone may include a number of stages, e.g., primary,secondary, tertiary cyclone stages, etc., wherein each successive stageremoves smaller and smaller particles. Suitable gas-solid separators invarious embodiments may alternatively or additionally include gravitysettling chambers, impingement separators, cyclone separators,mechanical centrifugal separators, granular-bed separators, bag filters,scrubbers, electrostatic precipitators, air filters, and the like,including combinations.

The fines-lean vapor from the cyclone 150 and/or tower 152 may befurther treated to remove hydrocarbons and other condensables via heatrecovery and condensation. For example, the vapor may be cooled andcondensate removed at a temperature above the boiling point of water inhigh temperature condenser 154, and then cooled and condensed in a lowtemperature condenser 156 at a temperature below the boiling point ofwater. The condensate from high temperature condenser 154 compriseshydrocarbons having a boiling point above that of water, and ispreferably essentially free of water, e.g., less than 1000 ppmw water orless than 100 ppmw water, and may be collected in a recovered oil tank158. The condensate from the low temperature condenser 156 may containboth oil and water and can be collected in a gravity separator 160 forrecovery of respective oil and water streams. The oil stream fromseparator 160 may be collected together with other recovered oil in tank158, or it may be a separate product stream of hydrocarbons with arelatively low boiling point or other specified characteristics. Thewater from the separator 160 may be further treated for disposal ifneeded, or recirculated as process or cooling water.

The non-condensed vapors from condenser 156 may optionally be exhaustedvia induced draft fan 162 and scrubber 164 to remove any residualparticulates, NOx, SOx, CO, CO2, other pollutants or the like.Alternatively or additionally, the vapor may be burned as fuel gas or,since it may contain appreciable amounts of hydrogen, carbon monoxideand/or carbon dioxide, used as a synthesis gas for any suitable processthat can utilize the gaseous reactants therein.

In an embodiment, at least a portion of the heat contained in the dilutephase exiting the thermal desorption zone, or anywhere along the vaporseparation system, may be recovered. In an embodiment, recovered heatmay be used to preheat the air used to produce the combustion effluentgas for the process. This may be done using a gas-gas indirect heatexchanger (not shown), a steam condensation loop (not shown), or the hotgases may be supplemented with oxygen and utilized again in thecombustion process (not shown).

Transportability

In an embodiment, the apparatus may be portable. The various componentsmay be mounted on one or more platforms, also referred to in the art as“skid mounted”, “truck mounted”, or the like, such that the apparatusmay be transported on a US Interstate highway either as a single unit,or on a plurality of platforms which are interconnected at the intendeddestination. The platforms may include wheels, brakes, signals and thelike (e.g., truck mounted on a flat-bed trailer) suitable for transporton a US Interstate highway, or the platforms may be mountable on a truckbed or rail car (skid mounted). In an embodiment, the one or moreplatforms are dimensioned and arranged for transportation such that eachof the mounted platforms has a total width of less than 2.59 meters (102inches), a total length of less than 13.71 meters (45 feet) and a totalheight of less than 4.27 meters (14 feet).

In an embodiment, the first and second housings and the burner aremounted on a first platform such that the mounted first platform has atotal width of less than 2.6 meters (102 inches), a total length of lessthan 13.7 meters (45 feet) and a total height of less than 4.2 meters(13.5 feet). In embodiments, the vapor recovery system is mounted on thefirst platform, or is mounted on a second platform of similar overalldimensions.

In one representative configuration as seen in FIGS. 11-14, wheeledtrailer 200 configured for operation in FIG. 11 has mounted thereonpeptizer 202 positioned on support structure 203 over desorber 204,forced draft fan 206 connected to firebox 208 and gas outlet pipe 210.Also, in operation conveyors 212, 214 are positioned to supply OBDC tofeed hopper 216 and to remove solids from the discharge from desorber204. Wheeled trailer 218 configured for operation in FIG. 12 has mountedthereon cyclone 220, knock-out tower 222, high temperature condenser224, low temperature condenser 226 and induced draft fan 228 positionedon support structure 230. In operation the desorber gas outlet pipe 210is connected to the cyclone inlet pipe 232, and a conveyor 234 may beprovided to remove fines from the bottom of the cyclone 220.

In transport mode as shown in FIGS. 13-14, the major equipment, e.g.,peptizer 202, desorber 204, fan 206, firebox 208, cyclone 220, tower222, condensers 224, 226 and fan 228, may be mounted in operatingposition and configuration, and, if desired, connecting lines such asconnector piece 236 and more portable equipment such as conveyors 212,214, 234 may be disconnected and secured to the trailers 200, 218 wherethere is space allowed. If desired or if needed, some of the majorequipment pieces may also be disassembled and secured on the trailers200, 218 to accommodate height, width or length restrictions.

Upon arrival at the site for treatment of ODBC, the conveyers 212, 214,234, transfer line 236 and any other disassembled equipment areconnected and installed for operation. Oil collection, gravity settling,water collection, etc., may be accomplished using fixed or portabletanks, e.g., tank trucks. When the solids treatment is completed, therig can be configured for transport and trucked to a new job location.

Accordingly, the invention provides the following embodiments:

-   -   A. A method, comprising: (a) peptizing a substrate at a        temperature between about 70° C. and about 105° C. with an        acidic reagent under shear to obtain a peptizate having        increased surface area, wherein the substrate comprises liquid        bound on a solid sorbent material, wherein the liquid comprises        oil or a mixture of oil and water, wherein the bound liquid        comprises less than about 35 wt % of the substrate, and wherein        the peptizate comprises a pH between 6 and 8; (b) mixing the        peptizate with a combustion effluent gas under turbulent        conditions in a thermal desorption zone to heat the peptizate        and desorb at least a portion of the oil from the sorbent        material, wherein the combustion effluent gas comprises less        than 1 vol % oxygen and is introduced into the thermal        desorption zone at a temperature greater than 300° C.; and (c)        separating the mixture into a dilute phase and a dense phase,        wherein the dilute phase comprises oil vapor and whereby the        sorbent material in the dense phase has an oil content less than        the oil content of the sorbent material in the substrate.    -   B. The method of embodiment A further comprising recovering the        dense phase sorbent material from the thermal desorption zone,        wherein the recovered sorbent material comprises less than or        equal to about 3 wt % residual oil.    -   C. The method of embodiment A or embodiment B, further        comprising recovering at least a portion of the oil from the        dilute phase, wherein the recovered oil comprises at least 50 wt        % of the oil in the substrate.    -   D. The method of any one of embodiments A to C, comprising        recovering at least a portion of the oil from the dilute phase,        wherein the oil in the bound liquid in the substrate comprises        more than 1 wt % aromatic hydrocarbons, by weight of the oil in        the bound liquid, wherein the recovered oil comprises less than        1 wt % aromatic hydrocarbons, by weight of the recovered oil,        and wherein the recovered oil has a viscosity of greater than 2        cSt at 40° C., wherein the viscosity is determined according to        ASTM-D88.    -   E. The method of any one of embodiments A to D, comprising        recovering at least a portion of the oil from the dilute phase,        wherein the recovered oil has one or more of lower aromatics        content, lower sulfur content, lower functional group content,        higher saturates, higher viscosity at 40° C., higher viscosity        index, and any combination thereof, relative to the oil bound to        the sorbent.    -   F. The method of any one of embodiments A to E, comprising        recovering at least a portion of the oil from the dilute phase        and further purifying the recovered oil to remove contaminants.    -   G. The method of any one of embodiments A to F, wherein the        combustion effluent gas has a temperature from 300° C. up to        1200° C.    -   H. The method of any one of embodiments A to G, comprising        recovering at least a portion of the oil from the dilute phase,        wherein a hydrocarbon fuel source for a combustion zone to        obtain the combustion effluent gas comprises at least a portion        of the recovered oil.    -   I. The method of any one of embodiments A to H, further        comprising supplying a temperature moderator to a combustion        zone to obtain the combustion effluent gas.    -   J. The method of any one of embodiments A to I, wherein the        dilute phase exits the thermal desorption zone at temperature of        from about 150° C. to about 300° C.    -   K. The method of any one of embodiments A to J, wherein the        peptizing zone has an average residence time from 5 seconds to 1        minute, and wherein the average residence time in the desorption        zone is from 10 seconds to 5 minutes for solids and from 1        second to 1 minute for vapor.    -   L. The method of any one of embodiments A to K, wherein the        acidic reagent comprises sulfuric acid supplied to the peptizing        zone in an amount from about 2 to about 12 wt %, by weight of        the substrate supplied to the peptizing.    -   M. The method of any one of embodiments A to L, wherein the        substrate comprises oil based drill cuttings.    -   N. The method of any one of embodiments A to M, wherein the        peptizing under shear comprises rotating at least one agitator        disposed longitudinally in a fixed housing containing a        peptizing zone, wherein the agitator comprises a shaft carrying        a plurality of impellors.    -   O. The method of any one of embodiments A to N, further        comprising rotating at least one agitator disposed        longitudinally in a fixed housing comprising the desorption        zone, wherein the agitator comprises a shaft carrying a        plurality of impellors.    -   P. An apparatus comprising: a substrate feed zone to supply a        charge of a substrate to a peptizing zone, the substrate        comprising a liquid bound on a solid sorbent material, wherein        the liquid comprises oil or a mixture of oil and water, wherein        the bound liquid comprises less than about 35 wt % of the        substrate; an acid feed system to supply an acid reagent to the        peptizing zone; one or more peptizing agitators to impart shear        into the peptizing zone to produce a peptizate; a transfer zone        to supply the peptizate from the peptizing zone to a thermal        desorption zone to vaporize oil from the peptizate; a burner in        fluid communication with the thermal desorption zone to supply        combustion effluent comprising less than 1 vol % oxygen to the        thermal desorption zone at a temperature greater than 300° C.;        one or more thermal desorption agitators to promote vapor-solid        mixing in the thermal desorption zone; a solids disengagement        zone in fluid communication between the thermal desorption zone        and a vapor recovery system; and a solids outlet from a housing        for the thermal desorption zone adjacent the solids        disengagement zone.    -   Q. The apparatus of embodiment P, wherein the thermal desorption        housing comprises an inlet for the combustion effluent and an        inlet for the peptizate at an inlet end opposite the solids        outlet for co-current operation.    -   R. The apparatus of embodiment P or embodiment Q, further        comprising a steady state control system comprising a        temperature sensor in the second housing and an acid reagent        addition rate controller responsive to temperature fluctuations        detected by the temperature sensor.    -   S. The apparatus of any one of embodiments P to R, wherein the        one or more thermal desorption agitators comprise a plurality of        blades rotatable on a longitudinal shaft, the apparatus further        comprising a refractory layer of the sorbent material formed        between an inner surface of the second housing and a cylinder        defined by rotation of the blades of the agitator about the        shaft.    -   T. The apparatus of any one of embodiments P to S, wherein the        thermal desorption zone comprises a ratio of length to diameter        of from 1 to 4, preferably from 1 to 2.    -   U. A transportable apparatus comprising: a feed hopper to supply        a charge of a substrate comprising a liquid bound on a solid        sorbent material to a peptizer comprising a first fixed housing        and one or more agitators; an acid feed system to supply an acid        reagent to react with the substrate in the peptizer and form a        peptizate; a transfer zone to supply the peptizate from the        peptizer to an inlet end of a thermal desorber comprising a        second fixed housing and one or more agitators, wherein the        transfer zone provides a seal to fluidly isolate the peptizer        from the thermal desorber; a burner in fluid communication with        the thermal desorber to supply a combustion effluent gas        comprising less than 1 vol % oxygen at a temperature greater        than 300° C. at the inlet end; a solids disengagement zone at an        outlet end of the thermal desorber opposite the inlet end for        co-current operation to separate a dilute phase from a dense        phase; a vapor outlet from the solids disengagement zone; a        solids outlet from the solids disengagement zone; and one or        more transportable platforms on which the feed hopper, acid feed        system, peptizer, burner, and thermal desorber are selectively        mounted in a transportation mode or in an operating mode.    -   V. The transportable apparatus of embodiment U, wherein the        mounted platforms in the transportation mode have an overall        width of less than 2.6 meters (102 inches), an overall length of        less than 13.7 meters (45 feet) and an overall height of less        than 4.1 meters (13.5 feet).    -   W. The apparatus of embodiment U or embodiment V, further        comprising a vapor recovery system in fluid communication with        the vapor outlet to receive the dilute phase, wherein the vapor        recovery system comprises at least one solids separator to        remove entrained fines, at least one condenser to recover liquid        and a gravity separator to obtain oil and water streams, wherein        the vapor recovery system is mounted on the one or more        transportable platforms.

EXAMPLES

The peptizing step in one embodiment is important to the success of theinstant process. In Comparative Example 1, an oil based drill cuttings(OBDC) substrate having 11 wt % water, 9.3 wt % oil, and 79.7 wt %solids was treated according to a comparative process using a lab scalesetup including a peptizer, an agitated direct thermal desorber, and acyclone, but without adding any acid to the peptizer The desorberagitator speed was 115 rpm with a tip speed of 1.1 m/s and the residencetime of the combustion effluent gas was about 3 seconds (27.7 m/min).The material from the peptizer was heated in the thermal desorber underturbulent conditions using co-current fuel-rich combustion effluent gasat 920° C. to obtain an outlet temperature of 220° C., which was subjectto cyclone separation to remove entrained solids, followed bycondensation and decanting to recover oil and water streams. Thesubstrate and liquid and solids product streams were measured andanalyzed for oil, water and solid contents and the results are presentedin Table 1.

TABLE 1 Mass Balance, Example 1 (Comparative) Component Substrate feed,Conc. H₂SO₄, kg Desorber solids, Fines, kg Oil Condensate, WaterCondensate, Stream kg (wt %) (wt % feed) kg (wt %) (wt %) kg (wt %) kg(wt %) Oil 6.7 (9.3) 3.1 (5.7) 0.21 (4.5) 3.0 (100) 0 Water  8 (11) 3.12(5.7)  0.14 (3.1) 0 8.9 (100) Solids 57.3 (79.7) 48.5 (88.6)  4.16(92.4) 0 0 Acid 0 (0) Total 72 0 48.5 4.51 3.0 8.9

In Example 1, only 44 wt % of the oil present in the substrate wasrecovered as a condensate and the residual oil on the solids recoveredfrom the desorber was 3 wt %. The additional water in the outputs isexplained by the presence of water in the combustion gas, which was notincluded in the mass balance.

In Example 2, an OBDC substrate having 23.4 wt % water, 11.6 wt % oil,and 65.0 wt % solids was treated using the same lab scale setup as inExample 1, except that sulfuric acid was added to the peptizer at a rateof 5.2 wt % by weight of the OBDC. The peptizate was heated in thethermal desorber under the same high shear conditions and fuel-richcombustion effluent gas at 920° C. to produce dense phase and dilutephase outputs at a temperature of 300° C., and the dilute phase was alsosubjected to cyclone separation as before to remove entrained solids,followed by heat exchange, condensation and decanting to recover oil.The higher desorber outlet temperature is explained by the exotherm fromthe reaction of the OBDC with the acid in the peptizer. The results arepresented in Table 2.

TABLE 2 Mass Balance, Example 2 Component Substrate feed, Conc. H₂SO₄,kg Desorber solids, Fines, kg Oil Condensate, Water Condensate, Streamkg (wt %) (wt % feed) kg (wt %) (wt %) kg (wt %) kg (wt %) Oil 11.6(11.6) 1.1 (3)  0.15 (5.1) 3.33 (100) 0 Water 12.64 (23.4)  0.74 (2.2)0.20 (6.7) 0 10.76 (98) Solids 35.1 (65.0) 31.66 (94.8)  2.65 (88.2) 00.21 (2) Acid 2.8 (5.2) Total 54 0 33.5 3.0 3.33 8.9

In Example 2, 53 wt % of the oil present in the substrate was recoveredand the residual oil on the recovered dense phase solids was 3 wt %,which was an improvement for the peptizing embodiment over thehigh-shear direct thermal desorption without acid addition in Example 1.The excess solids reported in the outputs is believed to be due to theformation of sulfate salts and other solid compounds formed as the acidreaction products in the peptizer.

In Example 3, another OBDC substrate having 19 wt % water, 11.6 wt %oil, and 69.4 wt % solids was treated according to the inventive processusing the same lab scale setup as in Examples 1 and 2, except that theconcentrated sulfuric acid was added to the peptizer at a rate of 7.8 wt% by weight of the OBDC. The peptizate was heated in the desorber usingcombustion effluent gas at 900° C. to obtain products at a temperatureof 275° C. The dilute phase was again subjected to cyclone separation toremove entrained solids, followed by heat exchange/condensation anddecanting to recover oil. The results are shown in Table 3.

TABLE 3 Mass Balance, Example 3 Component Substrate feed, Conc. H₂SO₄,kg Desorber solids, Fines, kg Oil Condensate, Water Condensate, Streamkg (wt %) (wt % feed) kg (wt %) (wt %) kg (wt %) kg (wt %) Oil  4.18(11.6) 0.26 (1.2) 0.25 (8.35)  3.03 (100) 0 Water 6.84 (19)  0.48 (2.2)0.12 (4)    0 7.72 (100)  Solids 24.98 (69.4)  21.5 (96.6) 2.63 (87.65)0 0.05 (>0.1) Acid 2.8 (7.8) Total 36 2.8 22 3   3.03   7.77

In Example 3, when the amount of acid was increased to about 8 wt % byweight of the OBDC, 72.5 wt % of the oil present in the substrate wasrecovered and the residual oil on the recovered dense phase solids wasnearly 1 wt %.

In Example 4, a test was conducted on a commercial scale (portable size)unit for a total time of operation of 7.25 hours using a 2.3 m diameteragitator assembly in a 3 m long thermal desorber with paddles on 195 mm(7.68-in.) spacing at 40 rpm. The test was conducted at a rate of 3.54metric tons/hr using OBDC obtained from a well site wherein the oilutilized was mainly diesel fuel with an aromatic content of up to about30 wt % according to the spec sheet. A total of 2066 L of oil wererecovered (82.3%) and the dense phase had a final wt % oil of 2.2%,reduced from 10.72 in the substrate feed. A total of 1030 L of dieselfuel were fed to the entire system including the burner and the dieselgenerator used to operate the equipment, to produce a net recovery of1036 L of oil from the process above fuel requirements. During theprocess, 2.37 L/min of diesel fuel was supplied to the burner to producethe combustion effluent gas utilized in the desorber. A total of 19,000L of water were used in the scrubber columns. The average residence timeof the solids was 40 seconds in the peptizer and 3 minutes in thethermal desorber. The peptizing zone volume was 1.8 m³ and the thermaldesorption zone volume was 22.8 m³.

In this test, the substrate feed was supplied to the peptizer along withconcentrated sulfuric acid at an average of 3.7 wt % by weight of theOBDC. The peptizer outlet temperature was between 80° and 100° C. Thepeptizate was fed into the desorber co-currently with a combustioneffluent gas supplied at a temperature of 1000° C. The temperature atthe outlets of the thermal desorption zone was maintained between 240°and 260° C. by adjusting the acid rate to the peptizer as needed. Thedense phase solids were recovered through a rotary valve. The dilutephase exited the thermal desorption zone and entered a cyclone separatorand entrained solids were recovered. Mechanical rodding of the transferline to the cyclone was used as needed to avoid plugging. Thesolids-lean gas exited the cyclone separator at a temperature between150° and 180° C. and entered a knock-out drum to further removeentrained solids. The gas exited the knock-out drum at a temperature of120° to 140° C. and was directed into a high temperature heat exchangerwherein oil and water were recovered. The uncondensed vapors exited theheat exchanger at a temperature between 40 and 60° C. and were thendirected into a low temperature condenser using cooling tower water(˜30° C.) as the cooling medium. The condensate from the low temperaturecondenser was gravity separated to recover the oil. The uncondensedvapors exited the scrubber column at a temperature between 33° and 35°C. and were vented.

The outputs were measured and analyzed, and the results are shown inTable 4. Note additional water recovery from the combustion effluent inthe outputs and additional solids believed to be due to sulfate additionsalts and other products from the acid added to the OBDC in thepeptizer.

TABLE 4 Mass Balance, Example 4 Component Substrate Conc. DesorberCyclone Knock- High Temp. Low Temp. Total Liquids feed, kg H₂SO₄, kgsolids, kg fines, kg out, kg Cond., kg Cond., kg Recovered, kg Stream(wt %) (wt % feed) (wt %) (wt %) (wt %) (wt %) (wt %) (% Recovered) Oil 2744.3 (10.7) 446 (2.2) 118.4 (6.3) 310.25 (38.8)  871.5 (8.4)    512(27.1) 1693.75 (61.7) Water   1920 (7.5) 360 (1.8)  26.3 (1.4) 408.8(51.1) 9544 (91.6)  1366.5 (72.4) 11705.6 Solids 20935.7 (81.8) 19194(96.0)  1735.2 (92.3) 80.95 (10.1) 0 (0)  9.9 (0.5) Acid 940 (3.7) Total25600 940 20000 1879.9 800 10416 1888.4

The solids recovered from the desorber had the particle sizedistribution given in Table 5.

TABLE 5 Desorber Solids Size Distribution, Example 4 Solids Mesh SizeRetained, Wt % 40 16.4 60 12.4 80 8.0 200  56.0 −200 (Fines) 7.2

The oil recovered from the process was analyzed and the results arepresented in Table 6.

TABLE 6 High Quality Oil Recovered, Example 4 Recovered Recovered Oil(High Oil (Low Temp. Temp. Parameter Test Method Condensate) Condensate)Specific Gravity @ ASTM-D1298 0.855 0.822 60° F. API Gravity API 33.82 —Flash Point Temp. ICOC, ASTM-D93 133 95 ° C. Ignition Temp. ICOC,ASTM-D56 146 — ° C. Pour Point, ° C. ASTM-D92 — −15 Total Ash, ppmASTM-D482 460 6 Heat Value, cal/g Calorimetry 10,982 — Viscosity @ 40°C., cSt ASTM-D88 5.61 3.45 Viscosity @ 100° C., cSt ASTM-D88 — 1.42Sulfur, wt % ASTM-1552 0.08 0.95 Carbon, wt % 86.43 — Hydrogen, wt %13.23 — Nitrogen, wt % 0.10 — Oxygen, wt % 0.114 — Aniline Point, ° C.ASTM-D611 69 68 Distillation ASTM-D88 Temp. @ 10% — 238.8 evaporated, °C. Temp. @ 50% — 268.7 evaporated, ° C. Temp. @ 90% — 321.3 evaporated,° C. Saybolt Color ASTM-D156-07 — −16 Cloud Point, ° C. ASTM-2500-09 —−13 BTEX Benzene, mg/L EPA 8260 — 0.282 Toluene, mg/L EPA 8260 — 0.242Ethylbenzene, mg/L EPA 8260 — 0.125 Xylenes, mg/L EPA 8260 — 0.348

As the data show, 61.7 wt % of the available oil was recovered as aliquid from the substrate. A rather unexpected result was theimprovement in the properties of the oil recovered. The composition ofthe oil recovered by the instant process is markedly different from thatof normal diesel fuel that was present in the oil based drill cuttingsused as substrate in the instant test. In fact, in view of the viscosityand aniline point, the recovered oil is suitable for use in a variety offunctions including oilfield functions, household/industrial cleaningproducts, metal rolling oil, paints and coatings, pesticideformulations, paper and milling chemicals, water treatment chemicals,and the like, consistent with other known refined mineral oils havingsimilar properties.

The uncondensed gases from the stack in Example 4 were analyzed anddetermined to contain 92-134 ppm CO, 7.3 vol % CO₂, 1 ppm NO_(x) as NO,no detectable H₂S, and had an explosivity (lower explosive limit in air)of 40 to 80 vol %.

The invention has been described above with reference to numerousembodiments and specific examples. Many variations will suggestthemselves to those skilled in this art in light of the above detaileddescription. All such obvious variations are within the full intendedscope of the appended claims.

What is claimed is:
 1. An apparatus comprising: a substrate feed zone tosupply a charge of a substrate to a peptizing zone, the substratecomprising a liquid bound on a solid sorbent material, wherein theliquid comprises oil or a mixture of oil and water, wherein the boundliquid comprises less than about 35 wt % of the substrate; an acid feedsystem to supply an acid reagent to the peptizing zone; one or morepeptizing agitators to impart shear into the peptizing zone to produce apeptizate; wherein the peptizing zone is fluidly sealed; a transfer zoneto fluidly isolate the peptizing zone from a thermal desorption zone andto supply the peptizate from the peptizing zone to an inlet end of thethermal desorption zone to vaporize oil from the peptizate; a burner influid communication with the inlet end of the thermal desorption zone tosupply combustion effluent comprising less than 1 vol % oxygen directlyinto the inlet end of the thermal desorption zone at a temperaturegreater than 300° C.; one or more thermal desorption agitators topromote vapor-solid mixing between the combustion effluent and thepeptizate in the thermal desorption zone; a solids disengagement zone influid communication between the thermal desorption zone and a vaporrecovery system; and a solids outlet from a housing for the thermaldesorption zone adjacent the solids disengagement zone.
 2. The apparatusof claim 1, further comprising a steady state control system comprisinga temperature sensor in the thermal desorption housing and an acidreagent addition rate controller responsive to temperature fluctuationsdetected by the temperature sensor.
 3. The apparatus of claim 1, whereinthe one or more thermal desorption agitators comprise a plurality ofblades rotatable on a longitudinal shaft, the apparatus furthercomprising a refractory layer of the sorbent material formed between aninner surface of the thermal desorption housing and a cylinder definedby rotation of the blades of the agitator about the shaft.
 4. Atransportable apparatus comprising: a feed hopper to supply a charge ofa substrate comprising a liquid bound on a solid sorbent material to apeptizer comprising a first fixed housing and one or more agitators,wherein the peptizer is fluidly sealed; an acid feed system to supply anacid reagent to react with the substrate in the peptizer and form apeptizate; a transfer zone to supply the peptizate from the peptizer toan inlet end of a thermal desorber comprising a second fixed housing andone or more agitators to promote vapor-solid mixing between thecombustion effluent and the peptizate, wherein the transfer zoneprovides a seal to fluidly isolate the peptizer from the thermaldesorber; a burner in fluid communication with the inlet end of thethermal desorber to supply a combustion effluent gas comprising lessthan 1 vol % oxygen at a temperature greater than 300° C. directly intothe thermal desorption zone at the inlet end; a solids disengagementzone at an outlet end of the thermal desorber opposite the inlet end forco-current operation to separate a dilute phase from a dense phase; avapor outlet from the solids disengagement zone; a solids outlet fromthe solids disengagement zone; and one or more transportable platformson which the feed hopper, acid feed system, peptizer, burner, andthermal desorber are selectively mounted in a transportation mode or inan operating mode, wherein the mounted platforms in the transportationmode have an overall width of less than 2.6 meters (102 inches), anoverall length of less than 13.7 meters (45 feet) and an overall heightof less than 4.1 meters (13.5 feet).
 5. The apparatus of claim 4,further comprising a vapor recovery system in fluid communication withthe vapor outlet to receive the dilute phase, wherein the vapor recoverysystem comprises at least one solids separator to remove entrainedfines, at least one condenser to recover liquid and a gravity separatorto obtain oil and water streams, wherein the vapor recovery system ismounted on the one or more transportable platforms.